Graco Turbo Booster, Britax boosters, Compass Brand
Stay away from Evenflo brand,my daughter(6) falls asleep and flops out of it, or the seat is to upright it pushes her forward. We have the one with the snazzy little built in lights for reading etc., looks cool the seat is horrible.
Compass brand boosters fold for traveling, I've heard great things about this one but have never tried it. I don't like that it doesn't have and head support for my sleeping kid.
My daughter(6)50lbs., is in the Britax Regent a harnessed carseat that will harness up to 80lbs. We both like this over any booster and feel safer. Although we do use a booster as a backup on occassion with traveling, carpooling, going in someone else's vehichle etc. I have had the best luck with the highback Graco Turbo Booster! And they have some in pretty girl colors or boy print to make it more fun!